Gas fired radiant tube burner



Jam 21, 1958 M. J. PARKER ET AL 2,820,447

GAS FIRED RADIANT TUBE BURNER Filed Jan. 16. 1956 2 Sheets-Sheet l Jan- 21, 1958 M. J. PARKERv ET AL 2,820,447

GAS F IRED RADIANT TUBE BURNER Filed Jan. 16. 1956 y 2 Sheets-Sheet 2 A 7mm/5x5.

United States Patent m' GAS FIRED RADlANT TUBE BURNER Melvin J. Parker, Garden City, and Alexander J. Turpin,

QStewart Manor, N. Y., assignors to Hauck Manufacturrug Co., Brooklyn, N. Y., a corporation of New York Application January 16, 1956, Serial No. 559,217

18 Claims. (Cl. 12o- 91) This invention relates to gas burners, particularly for firing into a tube.

Such a tube may be made of a special high temperature alloy and operate at red heat, the tube then being used for radiant heating. ln other cases the burner may fire into an immersion tube, and in still others it may lire into a finned tube for convection heating.

The radiant tube is the most common in use, compared to immersion or convection tubes. In the present specification these tubes, whether radiant, immersion or convection, will be referred to generically as heater tubes, for although heated by the burner llame, they are themselves used to heat something else.

The heater tube may be straight, or reversely bent to U shape, or doubly reversely bent to W shape or curved to shape, etc. 1n all cases the burner is disposed in one end of the tube, and hot gases are discharged at the other end, and ordinarily the ends will pass through and be supported by appropriate masonry. The primary object of the present invention is to generally improve gas burners for such tube tiring.

For tube firing the burner should produce an elongated slender llame, and one primary object of the present invention is to provide a gas burner which will produce such a llame. A further object is to provide means for controlling or adjusting the flame length over a Very Wide range. We have found that this may be done by using either, and preferably both, of two features. One feature is the use of a spinner or deflecting vane for whirling the air supply as it is admitted to the annular region be tween the gas tube and the heater tube. In tube firing the whirled air produces a lengthened flame. By making the deflecting vane angularly adjustable, and by providing a control lever and a dial and scale, the dellecting vane may be used to help control the flame length.

In accordance with another feature and object of the invention, a part of the air supply is admitted through ports into the gas tube, and the amount is controlled by a sleeve which is axially slidable on the gas tube. A part of the sleeve is preferably shaped to act as a valve for the air supplied outside the gas tube, and the arrangement is preferably such that movement of the sleeve in one direction reduces the air supply into the tube (the primary air) and increases the air supply around the tube (the secondary air), while movement in the other direction increases the primary air and decreases the secondary air. The former provides a long luminous llame while the latter provides a short sharp blue llame. This adjustment may be made from outside the burner, and thus helps provide the very wide range of adjustment previously mentioned. x

To accomplish the foregoing general objects, and other more specific objects which will hereinafter appear, our invention resides inthe gas burner elements, and their relation one to another and to the heater tube, as are hereinafter more particularly described in the following specification. The specification is accompanied by drawings, in which:

Fig. 1 is a partially sectioned longitudinal view of a gas burner embodying features of our invention;

2,820,447 Patented Jan. 21, 1958 .ice

Fig. 2 is a schematic view showing the burner applied to a U tube; Y'

Fig. 3 is a fragmentarylongitudinal section at the gas burner tip and llame retention nozzle;

Fig. 4 is an end view of the burner looking in the direction of the arrows 4-4 in Fig. 1;

Fig. 5 is a similar view, but partly sectioned approximately in the plane of the line 5-5 in Fig. 1; and

Fig. 6 is a transverse section taken approximately in the plane of the line 6-6 of Fig. l.

Referring to the drawing, and more particularly to Fig. 2, we there show a heater tube 12 of the reversely bent or U type. This may be made of a heat resistant alloy steel for operation as a radiant heater. The entrant end 14 Aof the tube passes through'a suitable masonry or irebrick or like heat resistant'wall 16. The discharge end 18 of the tube leads to a suitable' flue, here indicated at Ztl. The rear end of the burner is generally designated B, and it is secured to the entrant end 14 of heater tube 12, as by means of a plate 22 which is welded to the end of tube 14, and bolts which secure a flange 24 of the air body 26 to the plate 22. Air is supplied through pipe 28 and may be controlled by a valve 30. Gas is supplied through a pipe 32 and may be controlled by a Valve 34.

z The gas line is connected to a gas body 36 which is secured to the air bbdy 26.A High voltage electricity for ignition purposes may be supplied at an insulated terminal 38.

The air may be supplied at a pressure of, say, 4 to 32 oz. per square inch. The gas may be supplied at a pressure of, say, 2 to 32 oz.'4 per square inch. The valve 30 may be used to regulate the total amount of air (primary and secondary), or inthe case of a bank of burners, there may be a single automatic control valve which controls an entire bank of burners. The total air is determined by the need for complete combustion.

The showing in Fig. 2 is schematic rather than practical, for with vertical supply pipes, as shown, the heater tube would commonly be disposed in` a horizontal plane with both legs of equal length. With the U disposed in a vertical plane, as shown, the supply pipes would ordinarily run horizontally. Accordingly, in Fig. 2 the projection of the' burner leg of the heater tube at 14 is exaggerated, and would ordinarily :be a-matter of only a few inches l fromthe fire wall. The heat-'erl tube may have additional passes, and thus be W in shape instead of U in shape, and, on the other hand, mayy have a single pass, entering a furnace at one side and leaving on the other.

The burner may be described with reference irst to Fig. l of the drawing. `It comprises a tube 40 which receives gas or a mixtureof gas and primary air. A gas which is high in hydrogenfas in the case of most artificial gases, will require little or-no primary air. A gas whit-.his low in hydrogen, typically propane, butane, or natural gas,- will requiremore primarily air if ignition is to be maintained. 'Of course,l the total amount of air, primary and secondary, is fixed for a given rate of fuel consumption, in order to maintain complete combustion.

The tube 40 may be called a 'gas tube. lt terminates at its inner end in a burner tip-42, and the construction of this is better shown in Fig. 3. The air supply body 44 (Fig. 1) which surrounds the rear end of the tube 4t) supplies primary air through a series of ports 46 in tube 40 and supplies secondary air through an annular passage v48 around the tube.40-so that the secondary air ows between the tube 40 andthe main heater tube 14. The ports 46 are shown rectangular, but may have other shapes. The burner terminates in a flame retention nozzle 50 which has a diameter larger than the tube 40 and smaller than the lheatertube 14. The ame retention nozzle 50 is preferably nearly closed at its rear end by a plate 56, whichsurrouuds the burner tip 42, but which projects from and is readily visible well beyond the discharge end of a radiant tube twenty feet or more in length.

Reverting now to Fig. 1, the gas body 90 has a cylindrical forward end 92 which is received in a mating opening 94 in the air body 44. These parts are secured to gether as by means of a radial screw 96 (Fig. 4) received in a groove 97 (Fig. 1). The body 90 is rotatable relative to the body 44 so that the gas and air pipes can come into the burner in any desired direction. For example, the gas may come from beneath and the air from above. The tube 40 is secured to the gas body 90 by a press tit aided by a transverse drive pin (not shown). The burner tip 42 is secured to the tube 40 by a press fit aided by a transverse drive pin (not shown). The gas pipe is connected to the gas body 90, as by means of a ange connection 98. In the specific case here shown the flange connection is for a gas pipe, while the flange connection 80 is for a 11/2" air pipe, for a burner used in a 4 or radiant tube. This is mentioned by way of exam ple, and not as a limitation of the invention.

As is already known in the art, thin orifice plates may be inserted between the flange connections and the bodies, as a measure of regulation of the gas yand air supplies to help meet conditions at any particular installation, for gas may be available at one particular pressure, and air may be available at a very different pressure, because of equipment already installed and functioning at the plant for other purposes. It is also a safety feature against overloading the burner and the radiant tube which is made of expensive alloy, and should not be burned out.

The burner may be ignited in conventional fashion, by means of an electrode to which high tension electric current is supplied. Specifically, there is a terminal 38, having van insulation body 100 somewhat resembling a spark plug, and similarly screwed through a threaded opening. The conductor of the terminal is formed into a loop or eye at 102 where it receives a horizontal rod 104 which in turn passes through a cylindrical insulator 106 held in position by a clamp plate 108 and screw 110. The insulator may pass through the back plate 56 of the flame retention nozzle 50, and terminates in an inwardly turned electrode 112. The circuit is completed by a ground connection to the body of the burner.

The burner may be provided with an observation port, and this is shown at 114 in Figs. 1, 4, and 5. It includes a transparent window held in place by the hollow screw plug shown at 114. The small screw plugs 116 and 117 shown in Fig. 1 are for convenience in connecting a pressure gauge or manometer to the burner for test purposes.

The air supply body 44 includes a plate 120, in this case having a generally square shape which is best shown in Figs. 1, 4 and 5. This has holes at the corners to receive screws or bolts to mount the burner in position. For this purpose the radiant tube 14 terminates at its outer end in a plate 122 which may be welded to the end of the radiant tube, as shown at 124. The plate 122 is provided with holes aligned with the corner holes 126 of the burner, and thus the burner is mounted in place by securing plate 17.0 to plate 122.

One of the manufacturing advantages of the arrangement here disclosed is that the overall length of the burner may be varied while using standard parts at each end of the burner. It is only necessary to change the length of the tube 40 and the electrode rod 104. In practical application this is an important advantage because different installations require different overall length of burner. In all cases it is desirable that the frame retention nozzle 50 reach or nearly reach the inner face of the masory or firebriclc wall, as shown at 16 in Fig. 1 of the drawing. This is so because the heater tube 14 should not be exposed on the inside to llame and heat at a point where there would be no medium for effective dissipation of heat from the outside. Thus the thickness of the masonry wall 16 will itself be a factor in determining the minimum length of burner. Other.

factors may enter into-particular installations, such as asada?? Cll the room required for making pipe connections outside the furnace, or, in other words, the projection of the radiant tube 14 from the furnace, as shown in Fig. 2, and the nature of the due connection at the discharge end of the heater tubes when the tubes are of the U or W type.

it is believed that the construction and operation of our improved gas burner for tube firing, as well as the advantages thereof, will be apparent from the foregoing detailed description. The burner is made in several corresponding to large changes in diameter of the heater tube. Each burner size may be used with several dierent sizes of radiant tube, but a large change in tube size is accommodated by a change in burner size. The burner may be supplied in different lengths, depending on the requirements of the purchaser, and a change in length is readily accommodated at the factory, as previously explained.

The burner produces a flame the length of which is adjustable over a very wide range. In most practical cases the burner ame may be adjusted to be as long as the heater tube in which it is used. The flame length is adjusted by varying the ratio of primary air to secondary air by means of a convenient outside adjustment at 52, and also by varying the whirl of the air by means of the convenient outside adjustment 84.

The burner ignites easily and quietly. The formation of carbon is eliminated. The great length of the burner affords ample opportunity for the secondary air to move outward, aided by centrifugal force, before reaching the combustion zone.

It Will be understood that while we have shown and described our invention in a preferred form, changes may be made in the structure shown, without departing from the scope of the invention, as sought to be dened in the following claims. In the claims the reference to external adjustment means is not intended to exclude a control which is covered or concealed by a cap or plate to prevent unauthorized changes in adjustment. It refers preferably to a means which can be varied while the burner is in operation, so that the results of the adjustment maybe Watched.

We claim:

1. ln combination, a heater tube which is very long compared to its diameter and which is non-insulated and adapted to be used as a heat exchanger for providing intentional transfer of heat through the tube wall, and a burner which is long compared to its diameter and which has forward and rear portions connected by a primary tube, most of said burner being smaller in diameter than the heater tube and being inserted longitudinally of the heater tube into one end of the heater tube, said heater tube terminating in an outlet at its other end, said primary tube terminating at its inner end in a burner tip and having its rear end portion projecting from the heater tube, an air supply body surrounding the rear end portion of the primary tube and connected to a source of air to supply secondary air to flow outside the primary tube in the space ybetween the primary tube and the heater tube, a gas connection to the primary tube, ports in said primary tube within the air supply body to supply air to the primary tube for mixture with the gas in the primary tube, means in said air supply body to whirl the combustion air and cause it to as sume a helical path as it moves forward around the outside of the primary tube, said primary tube being designed to afford a straight flow therethrough, a sleeve valve slidable over the ports in said primary tube, external adjustment means for shifting said valve to vary the gas to air ratio in the primary tube, the forward end of said burner being designed to direct the ow thereat in axially forward direction, the combination serving to delay admixture of secondary air with the fuel in order to prolong the flame for more uniform heating of the heater tube along its length.

2. In combination, a heater tube which is very long asegure Compared t its diameter and which is nou-insulated and adapted to be used as a heat exchanger for vproviding 1ntentional transfer of Aheat through ythe tube wall, and a burner which is long vcompared to its diameter and which has forward and rear portions connected by a primary tube, most of said burner being smaller in diameter than the heater tube and being inserted longitudinally of the heater tube into one end of the heater tube, said heater tube terminating in an outlet at its other end, said primary tube terminating at its inner end in a burner tip and having its rear end portion projecting 'from the heater tube, an air suppiy body surrounding the rear end portion of the primary tube and connected to a source of air to supply secondary air to ilow outside the Vprimary tube in the space between the primary tube and .the heater tube, a connection to the primary tube, ports in said primary tube within the air supply body to supply air to the primary tube for mixture with the gas in the primary tube, amc retention means at the end of the primary tube, said means having a diameter larger than the primary tube and smaller than the heater tube, means in said air supply body to whirl the combustion air and cause it to assume a helical path as it moves forward around outside of the primary tube, said primary tube being designed to afford a straight flow therethrough, a sleeve vaive slidable over the ports Vin said primary tube, external adjustment means for shifting said valve to vary the gas to air ratio in the primary tube, the forward end of said burner being designed to direct the flow thereat in axialiy forward direction, the combination serving to delay adrnixture of secondary air with the fuel in order to prolong the ame for more uniform heating of the heater tube along its length.

3. combination, a heater tube which is very long compared to its diameter and which is non-insulated and adapted to be used as a heat exchanger for providing intentional transfer of heat through the tube wall, and a burner which is long compared to its diameter and which has forward and rear portions connected by a primary tube, most of said burner being smaller in diameter than the heater tube and being inserted longitudinally yof the heater tube into one end of the heater tube, said heater tube terminating in an outlet at its other end, Said primary tube terminating at its inner end in a burner tip and having its rear end portion projecting from the heater tube, an air supply body surrounding the rear end porn tion of the primary tube and connected to a source of air to supply secondary air :to flow outside the primary tube in the space between the primary tube and the heater tube, said air supply body having an annular passage to said space, a gas connection to the primary tube, ports in said primary tube within the a'ir supply body to supply air to the primary tube for mixture with the gas in the primary tube, ame retention means at the end of the primary tube, said means having a diameter larger than the primary tube and smaller than the heater tube, means in said air supply body to whirl the combustion air and cause it to assume a helical path as it moves -forward around the outside of the primary tube, said primary tube being designed to afford a straight flow therethrough, a sleeve valve slidable over the ports in said primary tube, external adjustment means for shifting said valve to vary the gas to air ratio in the primary tube, means to vary the size of the annular passage between the air supply body and the heater tube, the forward end of said l`burner being designed to direct the flow thereat in axially forward direction, the combination serving to delay admixture of secondary air with the fuel in Order to prolong the tiarne for more uniform heating of the 'heater tube along its length.

4. in combination, a heater tube which is` very long compared to its diameter and which is non-insulated and adapted to be used as a heat exchanger for providing intentional transfer of heat through the tube Wall, and a gas burner which is long compared `to its diameter and which has forward and rear portions connected by a primary tube, most of said burner being smaller in diameter than the heater tube and being inserted longitudinally of the heater tube into one end of the heater tube, said heater tube terminating 'in an `outlet at its other end, said primary tube terminating at its inner end in a burner tip and having its rear end portion projecting from the heater tube, an air supply body surrounding the rear end portion of the primary tube and connected to a source of air to supply secondary air to flow outside the primary tube in the space between the primary tube and the heater tube, said air supply body having an annular passage to said space, a gas connection to the primary tube, ports in said prim-ary tube within the air supply body to supply air to the primary tube for mixture with the gas in the primary tube, flame retention means at the end of the primary tube, said means having a diameter larger than the primary tube and smaller than the heater tube, means in said air supply body to whirl the combustion air and cause it to assume a helical path as it moves forward around the outside of the primary tube, said primary tube being designed to afford a straight flow therethrough, a sleeve valve slidable over the ports in said primary tube, external adjustment means for shifting said valve to vary the gas to air ratio in the primary tube, means to vary the size of the annular passage between the air supply body and the heater tube, Said means and sleeve being connected to simultaneously and oppositely vary the `siye of the primary and secondary air passages, the forward end of said burner being designed to direct the ow thereat in axially forward direction, the combination serving to delay admixture of secondary air with the fuel in order to prolong the flame for more uniform heating of the heater tube along its length.

5. ln combination, a heater tube which is very long compared to its diameter and which is non-insulated and adapted to be used as a heat exchanger for providing intentional transfer of heat through the tube wall, and a burner which is long compared to its diameter and which has forward and rear portions connected by a primary tube, most of said burner being smaller in diameter than the heater tube and being inserted longitudinally of the heater tube into one end of the heater tube, said heater tube terminating in an outlet at its other end, said primary tube terminating at its inner end in a burner tip and having its rear end portion projecting from the heater tube, an air supply body surrounding the rear end portion of the primary tube and connected to a source of air to supply secondary air to ow outside the primary tube in the space between the primary tube and the heater tube, said air supply body having an annular passage to said space, a gas connection to the primary tube, ports in said primary tube Within the air supply body to supply air to the primary tube for mixture with the gas in the primary tube, a sleeve valve slidable over the ports in said primary tube to vary the size of the air passage, external adjustment means for shifting said valve to vary the gas to air ratio in the primary tube, means to vary the size of the annular passage between the air supply body and the heater tube, said means and sleeve being connected to simultaneously and oppositely vary the size of the primary and secondary air passages, the for- Ward end of said burner being designed to direct the fiow thereat in axially forward direction, the combination serv ing to delay admixture of secondary air with the fuel in order to prolong the flame for more uniform heating of the heater tube along its length.

6. In. combination, a heater tube which is very long compared to its diameter and which is non-insulated and adapted to be used as a heat exchanger for providing intentional transfer of heat through the tube wall, and a burner which is long compared to its diameter and which has forward and rear portions connected by a primary tube, most of said burner being smaller in diameter than the heater tube and being inserted longitudinally of the heater tube into one end of the heater tube, said heater tube terminating in an outlet at is other end, said primary tube terminating at its inner end in a burner tip and having its rear end portion projecting from the heater tube, an air supply body surrounding the rear end portion of the primary tube and connected to a source of air to supply secondary air to flow outside the primary tube in the space between the primary tube and the heater tube, said air supply body having an annular passage to said space, a gas connection to the primary tube, ports in said primary tube within the air supply body to supply air to the primary tube for mixture with the gas in the primary tube, flame retention means at the end of the primary tube, said means having a diameter larger than the primary tube and smaller than the heater tube, a sleeve valve slidable over the ports in said primary tube to vary the size of the air passage, external adjustment means for shifting said valve to vary the gas to air ratio in the primary tube, means to vary the size of the annular passage between the air supply body and the heater tube, said means and sleeve being connected to simultaneously and oppositely vary the size of the primary and secondary air passages, the forward end of said burner being designed to direct the liow thereat in axially forward direction, the combination serving to de lay admixture of secondary air with the fuel in order to prolong the flame for more uniform heating of the heater tube alo-ng its length.

7. The combination defined in claim 1, in which the means to whirl the secondary air is an angularly adjustable defiecting vane in the air supply body together with external means for adjusting the position of the vane.

8. The combination defined in claim 2, in which the means to whirl the secondary air is an angularly adjustable defiecting vane in the air supply body together with external means for adjusting the position of the vane.

9. The combination defined in claim 3, in. which the means to whirl the secondary air is an angularly adjustable defiecting vane in the air supply body together with external means for adjusting the position of the vane.

10. The combination defined in claim 4, in which the means to whirl the secondary air is an angularly deflecting vane in the air supply body together with external means for adjusting the position of the vane.

11. The combination defined in claim 2, in which the fiame retention means is a nozzle having a cylindrical wall and an annular back plate, said back plate surrounding the primary tube but being radially spaced therefrom to provide an annular passage around the burner tip for forward fiow of a portion of the secondary air.

12. The combination defined in claim 4, in which the flame retention means is a nozzle having a cylindrical wall and an annular back plate, said back plate surrounding the primary tube but being radially spaced therefrom to provide an annular passage around the burner tip for forward flow of a portion of the secondary air.

13. The combination defined in claim 6, in which the ame retention means is a nozzle having a cylindrical wall and an annular back plate, said back plate surrounding the primary tube but being radially spaced therefrom to provide an annular passage around the burner tip for forward flow of a portion of the secondary air.

14. The combination defined in claim 3, in which the slidable sleeve valve around the primary tube has a rear portion axially movable over the air ports, and in which said means to vary the size of the annular passage comprises a forward conically-surfaced portion of said valve movable to variably obstruct the annular passage from the air supply body to the heater tube, whereby axial movement of said sleeve valve simultaneously and oppositely varies the size of the primary and secondary air supply openings.

15. The combination defined in claim 4, in which the slidable sleeve valve around the primary tube has a rear portion axially movable over the air ports, and in which said means to vary the size of the annular passage comprises a forward conicallysurfaced portion of said valve movable to variably obstruct the annular passage from the air supply body to the heater tube, whereby axial movement of said sleeve valve simultaneously and oppositely varles the size of the primary and secondary air supply openings.

16. The combination defined in claim l5, in which the slidable sleeve valve around the primary tube has a rear portion axially movable over the air ports, and in which said means to vary the size of the annular passage comprises a forward conically-surfaced portion of said valve movable to variably obstruct the annular passage from the air supply body to the heater tube, whereby axial movement of said sleeve valve simultaneously and oppositely varies the size of the primary and secondary air supply openings.

17. The combination defined in claim 16, in which the slidable sleeve valve around the primary tube has a rear portion axially movable over the air ports, and iu which said means to vary the size of the annular passage comprises a forward conically-surfaced portion of said valve movable to variably obstruct the annular passage from the air supply body to the heater tube, whereby axial movement of said sleeve valve simultaneously and oppositely varies the size of the primary and secondary air supply openings.

18. In combination, a heater tube which is very long compared to its diameter and which is non-insulated and adapted to be used as a heat exchanger for providing intentional transfer of heat through the tube wall, and a burner which is long compared to its diameter and which has forward and rear portions connected by a primary tube, most of said burner being smaller in diameter than the heater tube and being inserted longitudinally of the heater tube into one end of the heater tube, said heater tube terminating in an outlet at its other end, said primary tube terminating at its inner end in a burner tip and having its rear end portion projecting from the heater tube, an air supply body surrounding the rear end portion of the primary tube and connected to a source of air to supply secondary air to flow outside the primary tube in the space between the primary tube and the heater tube, said air supply body having an annular passage to said space, a gas connection to the primary tube, ports in said primary tube within the air supply body to supply air to the primary tube for mixture with the gas in the primary tube, ame retention means at the end of the primary tube, said means having a diameter larger than the primary tube and smaller than the heater tube, means in said air supply body to whirl the combustion air and cause it to assume a helical path as it moves forward around the outside of the primary tube, said primary tube being designed to afford a straight flow therethrough, means to vary the size of the annular passage between the air supply body and the heater tube, the forward end of said burner being designed to direct the flow thereat in axially forward direction, the combination serving to delay admixture of secondary air with the fuel in order to prolong the llame for more uniform heating of the heater tube along its length.

References Cited in the file of this patent UNITED STATES PATENTS 316,059 Randol Apr. 2l, 1885 593,904 Parfrey Nov. 16, 1897 821,419 Kemp May 22, 1906 1,781,236 Lilge Nov. 11, 1930 1,790,927 Kreager Feb. 3, 1931 2,117,270 Bloom May 17, 1938 2,602,440 Corns July 8, 1952 FOREIGN PATENTS 475,721 Great Britain Nov. 24, 1937 

